Surface coatings containing effect pigments, such as light absorbing pigment, light scattering pigments, light interference pigments, and light reflecting pigments are well known. Flakes, such as metallic flakes, for example aluminum flakes, are examples of such effect pigments and are especially favored for the protection and decoration of automobile bodies, such as for example by reason of their imparting a differential light reflection effect, usually referred, to as “flop”, as well as flake appearance effects, which include flake size distribution and the sparkle imparted by the flake as well as the enhancement of depth perception in the coating. The flake containing coatings usually also contain other pigments or colorants, generally of a light absorbing rather than a light scattering type. These light absorbing pigments interact with effect pigments such as flakes to change the appearance effect of the coating. In general, visual coating appearance includes texture, sparkle, glitter or other visual effects of a coating. The visual appearance can vary when viewed from varying viewing angles, with varying illumination angles, or with varying illumination intensities.
For repairing a previously coated substrate, for example, of an automotive body, it is necessary to choose the correct colorants or colorant combinations to match the color of that coated substrate as well as the correct effect pigments such as flakes to match the color and appearance of that coated substrate. Developments have been made to select colorants based on color measurement of a target coating. U.S. Patent Publication 2006/0181707, filed on May 6, 2004 with a U.S. application Ser. No. 10/552,200, described a computer implemented method to select colorants or colorant combinations to match the color of a coating on a coated auto body. Selection of effect pigments, such as flakes, however, is traditionally done manually by an experienced shader, based on their expertise. Once the flakes have been selected, the flakes are added into a formulation algorithm producing one or more preliminary matching formulas. One or more test coatings are then prepared based on the preliminary matching formulas and sprayed on test panels, which are then visually compared to the target coating. If the appearance such as flop and/or sparkle match are deemed unsatisfactory, the shader adjusts the type and/or changes the amount of the flakes entered into the algorithm to get new color/flop matching formulas and the whole cycle is repeated until an adequate match is achieved in both color and appearance at all angles of illumination and view. This traditional approach, however, requires repeated spraying and visually comparing test panels with the target coating.
A need exists, therefore, for a method for automatic selection of colorants and effect pigments such as flakes to produce one or more matching formulas wherein match coatings resulted from said matching formulas closely match both the color and appearance of the target coating.